The present invention relates to an operation apparatus for a vehicle automatic transmission mechanism, which comprises an actuator for driving a hydraulic valve for switching a travel range of the automatic transmission mechanism, and a transmission operation means for causing the actuator to execute a range switching operation.
A conventional operation apparatus for a vehicle automatic transmission mechanism comprises a select lever, as a manual transmission operation means, which is directly and mechanically connected to a hydraulic valve for switching a travel range of the automatic transmission mechanism, and is manually shifted by a driver. A driver shifts the select lever to a desired travel range position to switch a valve position of the hydraulic valve.
In a manual operation apparatus of this type, select levers are roughly classified into a floor type lever disposed between a driver's seat and a front passenger's seat, and a column type lever disposed on a sterring column.
In a conventional operation apparatus of an automatic transmission mechanism, when a travel range is to be switched, a driver must release his or her hand from a steering wheel, and regrips a select lever to shift it. On the other hand, upon switching of a shift position of a manual transmission mechanism, a driver must similarly release his hand from a steering wheel to regrip a shift lever.
In this manner, in order to perform a transmission operation (a travel range switching operation in an automatic transmission mechanism and a shift position switching operation in a manual transmission mechanism) in conventional transmission mechanisms regardless of an automatic or manual type, a driver must release one hand from a steering wheel to regrip a select or shift lever. During this interval, the driver grips the steering wheel with one hand, i.e., a single-hand driving state, and this state is not preferable in view of safety.
A driver tends to grow uneasy if he or she does not confirm a travel range position switched by himself or herself by visually observing an operation switch during driving of a vehicle. However, in a conventional automatic transmission mechanism comprising a floor type select lever, although a travel range indicator is provided to an instrument panel, it merely indicates a range position by an electrical signal in a strict sense, and a driver tends to shift his or her eye position from a front road to a select lever in a passenger room to confirm an indication position of the select lever disposed on the floor. Such a shift of an eye position can solve uneasiness of a driver but is not preferable from the viewpoint of safety driving.
When an operation range of another operation lever interferes with that of this operation switch, a driver must be careful not to operate another operation lever upon operation of this operation switch, and becomes careless of driving. It is not preferable in view of safety driving, either.
When a travel range is to be switched to a neutral range in a state wherein a travel range switching operation is performed among forward travel ranges, i.e., a forward drive range, a forward 2nd-speed range, and a forward 1st-speed range, if an operation force is too strong, a select lever may be erroneously set to a reverse range beyond the neutral range. In this manner, the reverse range is set by the automatic transmission mechanism during forward driving of a vehicle, which is undesirable.
Furthermore, when a forward travel range is set and a vehicle travels forward, if a body of a driver accidentally touches an operation switch due to immediate deceleration or abrupt braking, and a reverse range is erroneously set, it would also be undesirable.
In the above-mentioned manual operation apparatus, since the select lever and the hydraulic valve are directly and mechanically connected to each other via an arm, a link, and the like, a strong operation force is required to shift the select lever, and demand has arisen for an operation apparatus which requires only a light operation force.
In order to meet this demand, in recent years, for example, as disclosed in Japanese Patent Publication No. 63-37729, in an automatic transmission mechanism for a vehicle in which a hydraulic valve is controlled by a wire coupled to the hydraulic valve in a transmission to switch a travel range, a motorized range switching apparatus for driving the wire by a driving motor and operating the driving motor upon operation of an electrical switch has been proposed. According to the motorized range switching apparatus, a driver need only operate the electrical switch to switch the travel range through the driving motor. Thus, the driver can operate the electrical switch with a light operation force to instruct switching of the travel range.
However, in the conventional motorized range switching apparatus, a push-button switch is adopted as an electrical switch for instructing an operation of the driving motor. For this reason, when a driver switches a travel range position from a drive range to a 2nd-speed fixed range to perform a shift-down operation, he or she pays attention to the 2nd-speed fixed range switch to be pushed so as to prevent an erroneous operation. More specifically, in the conventional manual select lever, since all the travel range positions are linearly arranged like P-R-N-D-2-1, the select lever will never be directly shifted from the drive range position to the reverse range position. However, when the push-button switches are employed, if the reverse range switch is erroneously depressed during forward driving of a vehicle, a reverse travel state is set, it would be undesirable.
For this reason, a stroke contact type operation switch in which travel range positions to be set are sequentially juxtaposed along a predetermined path may be arranged as an electrical switch, thus reliably preventing erroneous depression. However, in the stroke contact type operation switch, when the operation switch is shifted to switch a travel range position, no target travel range position is specified at the beginning of the shift operation. When it is detected that the operation switch is stopped for a predetermined period of time, a travel range corresponding to the stop position is recognized as a target travel range to be selected. For this reason, when a travel range is to be changed based on this recognition result in practice in the automatic transmission mechanism, an actual change operation is started after the operation of the operation switch is completed, and an operation of the automatic transmission mechanism is considerably delayed. Thus, a driver undesirably feels uneasy.
In order to eliminate uneasiness, the following technique can be proposed. That is, when an operation switch is operated, its operation direction is detected, and a driving motor is driven according to the detected operation direction while a stop destination, i.e., a target travel range position is unknown, so that the travel range can be satisfactorily switched in response to an operation of the operation switch in the automatic transmission mechanism.
When the driving motor is driven according to an operation direction of the operation switch while a stop position is unknown, if the operation switch is held, for a long period of time, within a range which is set between adjacent operation range positions and in which a detection condition of a travel range is not established, the travel range of the automatic transmission mechanism may be undesirably set at a travel range position ahead of that to be set in the operation direction. In this manner, when a travel range of the automatic transmission mechanism is set at a travel range position different from that intended by a driver, this means that, for example, when a driver switches a travel range position from a forward 1st-speed range to a forward drive range, a reverse range or a parking range is undesirably set in the automatic transmission apparatus, and it is not preferable in terms of safety driving.
In the stroke contact type operation switch, when the operation switch is shifted to switch a travel range, the travel range in the automatic transmission mechanism must be precisely stopped at the travel range position switched by the operation switch. However, when a precise positioning operation cannot be executed in positioning/stop control, a problem on safety driving may be posed.
Furthermore, in the stroke contact type operation switch, when the operation switch is shifted to switch the travel range, the operation direction of the operation switch must coincide with the operation direction of the driving motor for switching the travel range in the automatic transmission mechanism. If a noncoincidence occurs, safety is impaired unless an error judgment is reliably performed.
Moreover, in the stroke contact type operation switch, when the operation switch is shifted to switch the travel range, if a driver continuously holds the operation switch at a halfway position, e.g., a position slightly offset from a position for setting a travel range, a reliable signal can no longer be output from the operation switch, and a travel range set by the operation switch cannot be determined for a long period of time, resulting in a problem on safety driving.